Just how hard do plants try to make as many seeds as possible? Much harder than you might think, notes Dave Nanda, a plant breeder and consultant for Seed Consultants, Inc.
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"The plant's mission is to produce as many 'babies' as possible," Nanda says. "It diverts energy from the stalk to the ear before black layer to ensure that the kernels it has chosen to make have every chance to be viable seeds."
Wait a minute – you don't plant hybrid corn again once you harvest it. Why is the plant worried about producing seeds? "The plant doesn't know that you won't be growing the seeds it produces," he says. "And if you've seen volunteer corn in a soybean field, you know ears can grow. It's just that the genetics in various plants will be inconsistent.
"The plant also doesn't care how much yield you get," he says. "It cares about survival of the fittest. That's why it does everything possible to try to produce at least some seed, and in many cases, as many viable seeds as possible."
To prove the point Nanda set up a demonstration in the Crop Watch field this year. He repeated it in both hybrids. However, it was not a replicated test.
At silking time, he removed the ears from three to four plants in a row. He marked the plants with red cloth so they could be identified later.
"We wanted to see if the plants would put out new ear shoots to try to make an ear and produce at least some seed," Nanda says. "In theory the plant can produce an ear at each node. If you remove the main ear, it can send out a shoot at the same node or next node down. If you removed that second ear after it starts to form, it should try to produce another ear. It can attempt to produce ears at more than one node."
When Nanda came back later in the season he found that for one hybrid, all three stalks where an ear was removed tried to put out another ear. One stalk sent out two ears from the same node.
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In the second hybrid, one stalk didn't put out an ear shoot, but the other stalk did. "The problem was that we were a bit late in starting the demonstration," he says. "By the time new shoots came out, there was little pollen left around."
No kernels on the slightly earlier-maturing hybrid appeared to have formed on the small ear shoots. However, on the slightly later-maturing hybrid, one small ear had kernels that appeared to be fertilized. Due to an insect boring into the stalk, the small ear fell off before it was possible to determine if the kernels would develop.
"We will try this again next year," Nanda says. "The point is that while you wouldn't think a plant would try to put out another ear if it loses one completely at the silking to brown silk stage, it will do so. The whole idea is to produce seed."